Error when running component

[Nurgak]

I would like to use visual odometry to get the pose of my robot, but I keep getting the following error when I run the component:

[VISO2 CONFIGURATION] Q re-projection matrix:
        1        0        0 -523.915
       0        1        0  -377.36
       0        0        0  774.932
       0        0 -8.30356        0
[VISO2 CONFIGURATION] Left Frame Error matrix:
 0.06887       0
      0 0.08192
[VISO2 CONFIGURATION] Right Frame Error matrix:
 0.07723       0
      0 0.08236
Press Enter to exit
[VISO2 LEFT_FRAME] Frame arrived at: 20170112-11:30:27:454246
1.787 [ ERROR  ][OrbRunner] in updateHook(): switching to exception state because of unhandled exception
1.787 [ ERROR  ][OrbRunner]   [VISO2] [FATAL ERROR]: transformation for transformer not found.

The problem seems to be stemming from the following lines in StereoOdometer.cpp:

/** Get the transformation (transformation) Tbody_left_camera which is body = Tbody_left_camera left_camera **/
if (_body_frame.value().compare(_left_camera_frame.value()) == 0)
{
    tf.setIdentity();
}
else if (!_left_camera2body.get(ts, tf, false))
{
    throw std::runtime_error("[VISO2] [FATAL ERROR]: transformation for transformer not found.");
    return;
}

I have no idea on how to proceed as the error message is not very explicit, what is the actual issue here?

[saarnold]

This task is using the transformer to lookup static and dynamic transformations and align them with it's input streams. This page gives an introduction how to setup the transformer in a ruby script: http://rock-robotics.org/master/documentation/data_processing/transformer_runtime.html Note that you have to require "transformer/runtime" in your script.

[jhidalgocarrio]

You also need to configure the coordinate frames for the transformer. You have an example at: https://github.com/exoter-rover/bundles-exoter/blob/master/config/orogen/viso2::StereoOdometer.yml

In case you want to have the visual odometry output in the camera frame just set body_frame=left_camera

[Nurgak]

Thanks @jhidalgocarrio and @saarnold, now that body_frame=left_camera it already gives me an idea of the error I might expect during runtime, I'll look into how/where/why to declare the transformers.